U.S. patent number 6,461,251 [Application Number 09/487,779] was granted by the patent office on 2002-10-08 for solid golf ball.
This patent grant is currently assigned to Bridgestone Sports Co, Ltd.. Invention is credited to Takashi Maruko, Yutaka Masutani, Hisashi Yamagishi.
United States Patent |
6,461,251 |
Yamagishi , et al. |
October 8, 2002 |
Solid golf ball
Abstract
In a solid golf ball of four or multi-layer construction,
comprising a center core, an outer core, an intermediate layer, and
a cover, the outer core has a higher Shore D hardness than the
center core, and the solid core has a diameter of up to 27 mm. The
ball has improved feel, click, durability and flight
performance.
Inventors: |
Yamagishi; Hisashi (Chichibu,
JP), Maruko; Takashi (Chichibu, JP),
Masutani; Yutaka (Chichibu, JP) |
Assignee: |
Bridgestone Sports Co, Ltd.
(Tokyo, JP)
|
Family
ID: |
16538006 |
Appl.
No.: |
09/487,779 |
Filed: |
January 20, 2000 |
Foreign Application Priority Data
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|
|
|
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Jul 22, 1999 [JP] |
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11-207332 |
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Current U.S.
Class: |
473/376 |
Current CPC
Class: |
A63B
37/0003 (20130101); A63B 37/04 (20130101); A63B
37/0031 (20130101); A63B 37/0043 (20130101); A63B
37/0062 (20130101); A63B 37/0076 (20130101); A63B
37/0092 (20130101) |
Current International
Class: |
A63B
37/04 (20060101); A63B 37/00 (20060101); A63B
37/02 (20060101); A63B 037/06 () |
Field of
Search: |
;473/376,373,378,371,377,374,367,368,369 |
References Cited
[Referenced By]
U.S. Patent Documents
|
|
|
5688595 |
November 1997 |
Yamagishi et al. |
5725442 |
March 1998 |
Higuchi et al. |
5980396 |
November 1999 |
Moriyama et al. |
|
Foreign Patent Documents
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|
|
|
|
|
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8-336617 |
|
Dec 1996 |
|
JP |
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9-56848 |
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Mar 1997 |
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JP |
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9-299510 |
|
Nov 1997 |
|
JP |
|
10-328328 |
|
Dec 1998 |
|
JP |
|
11-47309 |
|
Feb 1999 |
|
JP |
|
Primary Examiner: Graham; Mark S.
Assistant Examiner: Gordon; Reann
Attorney, Agent or Firm: Sughrue Mion, PLLC
Claims
What is claimed is:
1. A solid golf ball of multilayer construction of at least four
layers, comprising a solid core consisting of a center core and an
outer core around the center core, an intermediate layer of at
least one layer enclosing the solid core, said intermediate layer
closely enclosing the surface of said solid core and being formed
of a resin base composition, and a cover enclosing the intermediate
layer, wherein said outer core is formed of a thermoplastic resin
base composition and has a Shore D hardness higher than said center
core, and said solid core has a diameter of up to 27 mm, and said
intermediate layer closely enclosing the surface of said solid core
has a Shore D hardness which is at least 8 units higher than said
center core.
2. The solid golf ball of claim 1 wherein the Shore D hardness of
said outer core is from 55 to 85.
3. The solid golf ball of claim 1 wherein the Shore D hardness of
said outer core is at least 5 units higher than the Shore D
hardness of said center core.
4. The solid golf ball of claim 1 wherein at least one layer of
said intermediate layer has a lower Shore D hardness than said
outer core.
5. The solid golf ball of claim 1, wherein the diameter of the
center core is from 3 mm to 25 mm.
6. The solid golf ball of claim 1, wherein the Shore D hardness of
the center core is from 10 to 50.
7. The solid golf ball of claim 1, wherein the Shore D hardness of
the outer core is higher than the Shore D hardness of the center
core and the hardness difference is from 5 to 60.
8. The solid golf ball of claim 1, wherein the Shore D hardness of
the outer core is higher than the Shore D hardness of the center
core and the hardness difference is from 18 to 60.
9. The solid golf ball of claim 1, wherein the outer core has a
gage of from 1 mm to 10 mm.
10. The solid golf ball of claim 1, wherein the solid core has a
diameter of from 5 mm to 27 mm.
11. The solid golf ball of claim 1, wherein the cover has a Shore D
hardness of up to 65.
12. The solid golf ball of claim 1, wherein the intermediate layer
closely enclosing the surface of the solid core is formed of a
resin base composition selected from polyamide resins, ionomer
resins, polyester resins, polycarbonate resins, polyarylate resins,
ABS resins, and mixtures thereof.
13. The solid golf ball of claim 1, wherein the center core is
formed of a thermoplastic resin base composition.
14. The solid golf ball of claim 1, wherein the Shore D hardness
difference between the intermediate layer closely enclosing the
surface of the solid core and the center core is up to 45
units.
15. The solid golf ball of claim 1, wherein the Shore D hardness
difference between the intermediate layer closely enclosing the
surface of the solid core and the center core is up to 40
units.
16. The solid golf ball of claim 1, wherein the Shore D hardness of
the outer core is higher than the Shore D hardness of the center
core and the hardness difference is from 33 to 60.
17. The solid golf ball of claim 1, wherein the intermediate layer
has two layers of a first intermediate layer and a second
intermediate layer.
Description
This invention relates to a solid golf ball having satisfactory
sensory characteristics (e.g., feel and click) as well as improved
durability and flight performance.
BACKGROUND OF THE INVENTION
For a choice of golf balls, sensory reactions of the ball when hit
including an adequately soft feel and an agreeable click are now
regarded important. As is known in the art, upon driver or similar
shots causing substantial deformation of the ball, the player feels
the hardness of an internal region of the ball approximate to its
center. A variety of proposals of constructing the golf ball from
multiple layers were made for improving the sensory reactions as
described, for example, in JP-A 8-336617, 9-56848, 9-299510,
10-328328, and 11-47309. Many of these proposals, however, relate
to cores or center spheres having a relatively large diameter of
greater than 35 mm and even at minimum, a diameter of roughly 30
mm. They are not necessarily effective for improving feel.
It was also proposed to form a relatively soft center core to a
small diameter and enclose the small diameter center core with a
hard layer (enclosure or outer core). In this proposal, the outer
core is naturally made thick. However, enclosing a soft center core
with a hard outer layer substantially results in a core having a
large outer diameter. In the region where the ball undergoes
substantial deformation, for example, at the time of driver shots,
the player feels the hardness of the enclosure or outer core, which
feel sometimes becomes hard. If the outer core is too thick, the
ball becomes less durable due to the difference in hardness between
the center and outer cores.
SUMMARY OF THE INVENTION
An object of the invention is to provide a novel and improved golf
ball having satisfactory sensory characteristics when hit including
a soft feel and an agreeable click as well as improved durability
and distance performance.
The invention provides a solid golf ball of multilayer construction
of at least four layers, comprising a solid core consisting of a
center core and an outer core around the center core, an
intermediate layer of at least one layer enclosing the solid core,
and a cover enclosing the intermediate layer. The outer core has a
higher Shore D hardness than the center core. The solid core has a
diameter of up to 27 mm. Then the golf ball has satisfactory
sensory reactions upon impact including a soft feel and an
agreeable click. Additionally, the ball is fully durable and
travels a satisfactory distance.
Preferably, the outer core is formed of a thermoplastic resin base
composition. Preferably, the Shore D hardness of the outer core is
from 55 to 85 and is at least 5 units higher than the Shore D
hardness of the center core. At least one layer of the intermediate
layer preferably has a lower Shore D hardness than the outer core.
In one preferred embodiment, the intermediate layer closely
encloses the surface of the solid core, is formed of a resin base
composition, and has a Shore D hardness which is at least 2 units
higher than the Shore D hardness of the center core.
The Shore D hardness as used herein is measured according to ASTM
D-2240.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic cross-section of one exemplary multi-piece
solid golf ball according to the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The solid golf ball of the invention has a multilayer construction
of at least four concentric layers. Specifically, the ball includes
a solid core including a center core 10 and an outer core 12 around
the center core 10, an intermediate layer 14 of at least one layer
enclosing the solid core, and a cover 16 enclosing the intermediate
layer 14. The intermediate layer 14 may include at least a first
intermediate layer 18 and a second intermediate layer 20.
Specifically the ball includes a solid core consisting of a center
core and an outer core around the center core, an intermediate
layer of at least one layer enclosing the solid core, and a cover
enclosing the intermediate layer.
The center core is a center sphere of the ball and may be formed of
a composition primarily comprising a thermoplastic resin or
rubber.
The thermoplastic resins used herein include well known ones, for
example, polyamide resins, ionomer resins, polyester resins,
polycarbonate resins, polyarylate resins, ABS resins, and mixtures
thereof. These resins are commercially available under the trade
name of Surlyn (ionomer resins) from E. I. DuPont, Himilan (ionomer
resins) from Dupont-Mitsui Polychemical Co., Ltd., Hytrel
(polyester resins) from Dupont-Toray Co., Ltd., Rilsan BMNO
(polyamide resins) from Dupont-Toray Co., Ltd., U Polymer
(polyarylate resins) from Unitika, Ltd., UBE Nylon (polyamide
resins) from Ube Kosan Co., Ltd., and Pandex (polyurethane resins)
from Dai-Nippon Ink & Chemicals Co., Ltd.
In the thermoplastic resins, inorganic fillers such as barium
sulfate, titanium dioxide and zinc oxide may be blended as a weight
modifier.
Where the center core is formed of the thermoplastic resins,
injection molding or similar molding techniques may be used, with
optimum molding conditions being selected in accordance with a
particular formulation.
In the other embodiment where the center core is formed of rubber,
a rubber composition comprising polybutadiene as the base rubber is
appropriate. The use of cis-1,4-polybutadiene having a cis
structure of at least 40% is especially suitable. Where desired,
other suitable rubber ingredients such as natural rubber,
polyisoprene rubber or styrene-butadiene rubber may be compounded
with the polybutadiene to give the base rubber. Up to about 10
parts by weight of the other rubber ingredients may be compounded
per 100 parts by weight of the polybutadiene.
A crosslinking agent may be included in the rubber composition.
Exemplary crosslinking agents are the zinc and magnesium salts of
unsaturated fatty acids such as methacrylic acid and acrylic acid,
and ester compounds such as trimethylpropane methacrylate. Zinc
diacrylate is especially preferred for achieving a high resilience.
The crosslinking agent is preferably included in an amount of about
10 to 40 parts by weight per 100 parts by weight of the base
rubber.
A vulcanizing agent is generally compounded in the rubber
composition. Organic peroxides are preferred vulcanizing agents.
Examples of suitable peroxides include commercially available
products such as Perhexa 3M (manufactured by Nippon Oils and Fats
Co., Ltd.). The amount of vulcanizing agent included in the rubber
composition is preferably from about 0.6 to 2 parts by weight per
100 parts by weight of the base rubber.
If necessary, other suitable ingredients may also be blended in the
rubber composition, such as antioxidants and specific
gravity-modifying fillers (e.g., zinc oxide, barium sulfate). The
amount of such specific gravity modifiers blended is typically more
than about 0.5 parts, especially more than about 1 part and less
than about 30 parts by weight per 100 parts by weight of the base
rubber.
Where the center core is formed from the rubber composition, the
composition may be molded and vulcanized by a conventional
procedure, for example, under conditions of 155.degree. C. and 20
minutes.
It is recommended that the center core is formed to a diameter of
at least 3 mm, preferably at least 5 mm, more preferably at least 7
mm and up to 25 mm, preferably up to 24 mm, more preferably up to
23 mm. A center core with too small a diameter may be ineffective
whereas too large a diameter may lead to a hard feel and a loss of
durability.
The center core preferably has a Shore D hardness of at least 10,
especially at least 15 and up to 55, especially up to 50, though
not limited thereto.
Next, the outer core enclosing the center core may be composed
mainly of a resinous material or a rubber base composition.
Especially for imparting agreeable sensory characteristics to the
ball, the use of resinous materials is preferred. Use may be made
of the thermoplastic resins listed above in conjunction with the
center core. Included are polyamide resins, ionomer resins,
polyester resins, polycarbonate resins, polyarylate resins, ABS
resins, and mixtures thereof. These resins are commercially
available under the trade name of Surlyn (ionomer resins) from E.
I. DuPont, Himilan (ionomer resins) from Dupont-Mitsui Polychemical
Co., Ltd., Hytrel (polyester resins) from Dupont-Toray Co., Ltd.,
Rilsan BMNO (polyamide resins) from Dupont-Toray Co., Ltd., U
Polymer (polyarylate resins) from Unitika, Ltd., UBE Nylon
(polyamide resins) from Ube Kosan Co., Ltd., and Pandex
(polyurethane resins) from Dai-Nippon Ink & Chemicals Co.,
Ltd.
The outer core is formed on the surface of the center core by an
injection molding process of placing the center core in a mold and
injection molding the resinous material around the center core. An
alternative is a compression molding process involving forming
thermoplastic resin sheets into a pair of hemispherical cups,
placing the center core in one cup, closing the other cup over the
center core, and effecting molding under heat and pressure.
Where the rubber composition is used in the outer core, a
polybutadiene base rubber composition as described for the center
core may be used as well. In forming the outer core from the rubber
composition, one suitable method is a two-step process in which the
rubber composition is first subjected to primary vulcanization
(semi-vulcanization) in a mold to form a pair of hemispherical
cups. A preformed center core is then placed in one of the
hemispherical cups, the other cup is closed over the center core,
and secondary vulcanization (complete vulcanization) is carried
out.
According to the invention, the Shore D hardness of the outer core
should be higher than the Shore D hardness of the center core. An
appropriate hardness difference is at least 5 units, preferably at
least 10 units, more preferably at least 18 units in Shore D
hardness. By establishing such a hardness difference, the objects
of the invention are more readily attained. The upper limit of the
hardness difference is usually up to 60 units, especially up to 50
units in Shore D hardness. If the Shore D hardness of the outer
core is equal to or lower than the Shore D hardness of the center
core, then the objects of the invention are not attainable.
While a particular hardness of the outer core may be adjusted in
accordance with the hardness of the center core, it is recommended
that the Shore D hardness of the outer core is at least 55,
preferably at least 56, more preferably at least 57 and up to 85,
preferably up to 84, more preferably up to 83. An outer core with a
lower Shore D hardness may lead to low resilience and less
agreeable sensory characteristics, whereas an outer core with a
higher Shore D hardness may lead to less durability and a hard
feel.
It is recommended that the outer core have a radial thickness or
gage of up to 10 mm, preferably up to 8 mm, more preferably up to 7
mm and at least 1 mm, preferably at least 1.3 mm, more preferably
at least 1.5 mm. An outer core with a smaller gage may lead to poor
durability whereas an outer core with a larger gage may lead to a
hard feel. However, a particular gage of the outer core may be
adjusted in accordance with the diameter of the center core. As
long as the diameter of the solid core is within 27 mm, the outer
core may be made relatively thick when the center core is small,
and inversely, the outer core may be made relatively thin when the
center core is large. By adjusting the gage of the outer core in
this way, the problem of a hard feel resulting from a too thick
outer core in the prior art can be avoided. Further adjustment can
be made by lowering the Shore D hardness of the center core and in
accordance with the material and hardness of the intermediate layer
surrounding the outer core.
The solid core composed of a center core enclosed within an outer
core as described above has a relatively small diameter of up to 27
mm, preferably up to 26 mm, and especially up to 25 mm. The lower
limit is preferably 5 mm, more preferably 7 mm, and especially 8
mm. A solid core having a too small diameter may be ineffective
whereas a solid core having a too large diameter falls within the
concept of the prior art, leading to a hard feel, unsatisfactory
click and less durability.
In the golf ball of the invention, an intermediate layer of one or
more layers is formed on the surface of the outer core. The
intermediate layer may be formed of any resinous materials or
rubber compositions as described above for the center core and the
outer core, preferably resinous materials. The intermediate layer
closely enclosing the outer core (referred to as first intermediate
layer) is preferably formed of the above-mentioned resinous
materials. Included are polyamide resins, ionomer resins, polyester
resins, polycarbonate resins, polyarylate resins, ABS resins, and
mixtures thereof. These resins are commercially available under the
trade name of Surlyn (ionomer resins) from E. I. DuPont, Himilan
(ionomer resins) from Dupont-Mitsui Polychemical Co., Ltd., Hytrel
(polyester resins) from Dupont-Toray Co., Ltd., Rilsan BMNO
(polyamide resins) from Dupont-Toray Co., Ltd., U Polymer
(polyarylate resins) from Unitika, Ltd., UBE Nylon (polyamide
resins) from Ube Kosan Co., Ltd., and Pandex (polyurethane resins)
from Dai-Nippon Ink & Chemicals Co., Ltd. As compared with
rubber compositions enclosing the hard outer core, the use of
resinous materials is effective for minimizing the cracking at the
interface and maintaining durability. On use of these resinous
materials, the molding processes described for the outer core are
employable.
In order to effectively achieve the objects of the invention, the
intermediate layer preferably includes at least one layer having a
lower hardness than the outer core. Typically the first
intermediate layer is the layer having a lower hardness than the
outer core. Where the intermediate layer consists of a plurality of
layers, it is preferred that all the layers be softer than the
outer core. More particularly, the first intermediate layer closely
enclosing the outer core preferably has a Shore D hardness which is
at least 5 units, more preferably at least 7 units lower than the
Shore D hardness of the outer core. Differently stated, the outer
core is at least 5 units, more preferably at least 7 units harder
than the first intermediate layer. The maximum difference in
hardness between the outer core and the first intermediate layer is
preferably 65, and more preferably 60. Further preferably the first
intermediate layer is harder than the center core because not only
a soft feel is obtainable, but agreeable sensory characteristics
and better durability are also achievable. An appropriate hardness
difference between the first intermediate layer and the center core
is at least 2 units, more preferably at least 3 units, especially
at least 5 units, and up to 45 units, especially up to 40 units, in
Shore D hardness.
Specifically, the first intermediate layer may have a Shore D
hardness of at least 10, especially at least 15 and up to 80,
especially up to 70. Where the intermediate layer consists of a
plurality of layers, the layers other than the first intermediate
layer may have a Shore D hardness in the same range as above.
The solid core enclosed with the intermediate layer generally has
an outer diameter of at least 36 mm, preferably at least 37.5 mm
and up to 41.5 mm, preferably up to 39.5 mm.
The golf ball of the invention is made by forming a cover around
the intermediate layer. The cover may be made of any well-known
cover stock material. Illustrative are ionomer resins,
thermoplastic polyurethane, polyamide, and polyester elastomers,
and balata rubber. The cover may be formed by conventional
injection molding and other processes.
Preferably the cover has a thickness of at least 0.5 mm, especially
at least 0.8 mm and up to 3.0 mm, especially up to 2.5 mm. It is
recommended that the cover have a Shore D hardness of at least 40,
preferably at least 50 and up to 70, preferably up to 65. A cover
with a lower hardness may lead to a resilience loss whereas a cover
with a higher hardness may lead to a durability loss. It is
recommended that the cover have a specific gravity of 0.9 to
1.4.
As in conventional golf balls, the golf ball of the invention has
300 to 600 dimples formed on the surface of the cover and
distributed in a well-known arrangement.
The golf ball of the invention should be formed so as to have a
diameter and weight which conform with the Rules of Golf.
Specifically, the ball may have a diameter of not less than 42.65
mm, especially not less than 42.67 mm and not greater than 42.75
mm, and a weight of not greater than 45.93 g, especially not
greater than 45.90 g and not less than 45.10 g.
EXAMPLE
Examples of the invention and comparative examples are given below
by way of illustration, and are not intended to limit the
invention.
Examples 1-4 and Comparative Examples 1-3
In each example, a center core was produced using the center
core-forming composition of the formulation shown in Table 1. More
particularly, resin compositions were injection molded in Examples
1 to 3 and Comparative Example 3. Rubber compositions were molded
and vulcanized in Example 4 and Comparative Examples 1 and 2.
Next, an outer core-forming thermoplastic resin composition of the
formulation shown in the table was injection molded around the
center core in each example excluding Comparative Examples 2 and 3,
to form an outer core, yielding a solid core having the center core
enclosed with the outer core.
In each of Examples 1 to 4, a first intermediate layer-forming
thermoplastic resin composition of the formulation shown in the
table was injection molded around the solid core to form a first
intermediate layer. In Example 2 only, a second intermediate layer
was formed around the first intermediate layer by injection molding
a second intermediate layer-forming thermoplastic resin composition
of the formulation shown in the table. There was obtained a sphere
having the solid core enclosed with an intermediate layer of
two-layer structure.
In each of Comparative Examples 1 to 3, a first intermediate
layer-forming rubber composition of the formulation shown in the
table was worked in a roll mill and subjected to primary
vulcanization (semi-vulcanization) at 130.degree. C. for 10 minutes
to form a pair of hemispherical cups. The pair of cups was closed
over the solid core (center core+outer core) in Comparative Example
1 or directly over the center core in Comparative Examples 2 and 3,
following which the cups were subjected to secondary vulcanization
(complete vulcanization) at 155.degree. C. for 20 minutes to give a
sphere having the first intermediate layer.
Around the sphere having the intermediate layer formed, a
cover-forming material of the formulation shown in the table was
injection molded to form a cover. In this way, golf balls having
dimples of the same shape, arrangement and number were
produced.
Among the ingredients shown in the table, the trade names have the
following meaning. Hytrel: thermoplastic polyester elastomers
manufactured by Dupont-Toray Co., Ltd. Rilsan BMNO: thermoplastic
polyamide elastomer manufactured by Toray Industries, Inc.)
Himilan: ionomer resins manufactured by DuPont-Mitsui Polychemical
Co., Ltd. Surlyn: ionomer resins manufactured by E. I. DuPont de
Nemours and Co. Pandex: thermoplastic polyurethane elastomers
manufactured by Dai-Nippon Ink & Chemicals Co., Ltd.
The resulting golf balls were evaluated for durability, flight
performance and sensory characteristics as described below. The
results are presented in Table 1.
Durability
The ball at a randomly selected point was consecutively struck with
a club. The number of strikes was counted until the ball was
cracked. The number of strikes on the ball of Example 1 was
acceptable. When the number of strikes was at least 10% smaller
than Example 1, that ball was rated "Poor."
Flight Performance
Using a swing robot (Miyamae K.K.) equipped with a driver, the ball
was hit at a head speed of 40 m/s (HS40). A carry and total
distance were measured.
Sensory Characteristics when Hit
A sensory test was made by five professional golfers and five top
amateur golfers who actually hit the ball. The ball was rated for
feel by examining whether it was felt soft to the hands and for
click by examining whether it sounded agreeable. The ball was rated
"Poor (Hard)" when the results were inferior, "Fair" when the
results were relatively inferior, and "Good (Soft)" when the
results were superior.
TABLE 1 Ingredients (pbw) E1 E2 E3 E4 CE1 CE2 CE3 Center core
Formulation Hytrel 3078 100 Hytrel 3548 100 Hytrel 4047 100 Rilsan
BMNO 100 cis-1,4-polybutadiene 100 100 100 Zinc oxide 5 5 5 Zinc
diacrylate 5 23 28 Dicumyl peroxide 1.2 1.2 1.2 Barium sulfate 5 37
32 16 40 Parameters Diameter (mm) 15 18 24 11 15 32 25 Weight (g)
2.0 3.4 8.3 0.8 2.2 20.2 10.9 Shore D hardness 35 40 30 33 50 45 80
(ASTM D-2240) Outer core Formulation Himilan AM7318 50 50 Himilan
AM7317 50 50 Himilan 1706 50 50 Himilan 1605 50 50 Himilan 1650 50
Surlyn 8120 50 Barium sulfate 10 5 5 10 Parameters Diameter (mm) 20
24 27 26 30 Weight (g) 4.5 7.6 11.4 9.5 14.4 Gage (mm) 2.5 3.0 1.5
7.5 7.5 Shore D hardness 69 58 63 69 63 (ASTM D-2240) Hardness
difference (outer core - center core) 34 18 33 36 13 1st
Formulation Pandex T-8195 100 intermediate Hytrel 4767 100 100
layer Surlyn 8120 50 Himilan 1650 50 cis-1,4-polybutadiene 100 100
100 Zinc oxide 5 5 5 Zinc diacrylate 23 30 37 Dicumyl peroxide 1.2
1.2 1.2 Barium sulfate 4 3 33 7 48 14 5 Parameters Diameter (mm)
38.9 36.7 38.9 38.7 38.1 38.7 38.7 Weight (g) 35.7 30.5 35.7 35.2
33.9 35.2 35.2 Shore D hardness 49 48 56 47 50 54 60 (ASTM D-2240)
Hardness difference 20 10 7 22 13 -- -- (outer core - 1st
intermediate layer) Hardness difference 14 8 26 14 0 9 -20 (1st
intermediate layer - center core) 2nd Formulation Himilan 1605 50
intermediate Himilan 1706 50 layer Barium sulfate 10 Parameters
Diameter (mm) 39.7 Weight (g) 37.5 Specific gravity 1.023 Shore D
hardness 63 (ASTM D-2240) Cover Formulation Himilan 1605 50 50 50
50 50 50 Himilan 1706 50 50 50 50 50 50 Surlyn 8120 50 Himilan 1650
50 Parameter Gage (mm) 1.9 1.5 1.9 2.0 2.3 2.0 2.0 Ball Parameters
Diameter (mm) 42.7 42.7 42.7 42.7 42.7 42.7 42.7 Weight (g) 45.3
45.3 45.3 45.3 45.3 45.3 45.3 Durability Good Good Good Good Poor
Poor Poor HS40 Carry (m) 198.0 199.0 198.6 199.0 196.5 197.0 197.6
Total (m) 210.0 210.5 211.0 210.8 207.0 207.9 208.6 Sensory Feel
Soft Soft Soft Soft Fair Soft Fair characteristics Click Good Good
Good Good Fair Poor Fair
Note that the diameter and weight in Parameters are those of an
entire sphere having the designated layer formed.
There has been described a golf ball which is improved in sensory
characteristics including feel and click when hit with a golf club,
durability against strikes, and flight performance.
Japanese Patent Application No. 11-207332 is incorporated herein by
reference.
Although some preferred embodiments have been described, many
modifications and variations may be made thereto in light of the
above teachings. It is therefore to be understood that the
invention may be practiced otherwise than as specifically described
without departing from the scope of the appended claims.
* * * * *